The present invention relates to microbial xyloglucan endotransglycosylases (XETs) and the production and uses thereof.
Xyloglucan endotransglycosylase (XET) is an enzyme known from plants. To our best knowledge XET has never been described from microorganisms.
Stephen C. Fry et al. suggest in Biochem. J (1992) 282, p. 821-828 that XET is responsible for cutting and rejoining intermicrofibrillar xyloglucan chains and that XET thus causes the wall-loosening required for plant cell expansion.
XET has been suggested for use in regulating the morphology of a plant, see EP 562 836 p. 2 1. 27-28.
XET is believed to be present in all plants, in particular in all land plants. XET has been extracted from dicotyledons, monocotyledons, in particular graminaceous monocotyledons and liliaceous monocotyledons, and also from a moss and a liverwort, for reference see Biochem. J (1992) 282, p. 823.
In the copending patent application PCT/DK 96/00538 (WO 97/23683) we have shown that a cellulosic material may get improved strength properties and/or improved shape-retention properties and/or improved anti-wrinkling properties after treatment with an XET enzyme.
The XET enzyme has some very interesting applications, so it is an object of the present invention to provide microbially derived xyloglucan endotransglycosylases useful for, e.g., the applications described above. The microbially derived xyloglucan endotransglycosylases would have the great advantage that they could easily be produced in great quantities.
It has been found by a screening assay that XET activity is produced by an overwhelming array of phylogenetically dispersed microorganisms.
Accordingly, the present invention relates to a xyloglucan endotransglycosylase preparation which is producible by cultivation of a microorganism expressing an XET; in particular the present invention relates to:
A method for the production of a xyloglucan endotransglycosylase enzyme (XET) comprising
(a) culturing in a suitable nutrient medium a microorganism expressing a microbial XET under conditions conducive to the production of the XET enzyme, and
(b) subsequently recovering of the XET enzyme from the nutrient medium.
Further, the present invention relates to use of the XET preparation of the present invention for treating cellulosic material, and to microbial XET preparations as such.